Embryo Anomalies Flashcards
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duct can persist and form a cyst in the tongue or anterior portion of the neck»_space; may perforate the skin after an infection to become a thyroglossal duct sinus
thyroglossal duct cysts
over 5% of the population has an abnormal number or abnormal distribution pattern
variation in vertebra number
chondrification center fails to form on one side of vertebral body»_space; half of vertebra never forms
produces lateral curvature of the spine or scoliosis (other causes as well)
hemivertebra
failure of the calvaria to develop»_space; other severe anomalies concurrent
acrania
deformities resulting from premature closure of sutures
different forms determined by which suture closed prematurely
craniosynostosis
occurs in ~1% of infants but asymptomatic until adulthood
anomalies of the craniovertebral junction
autosomal dominant trait resulting in lack of long bone elongation
characterized by large head, normal torso and short limbs
achondroplasia
excessive secretion of growth hormone resulting in giantism
congenital hyperpituitarism
result of hypersecretion of growth hormone after epiphyseal plate has closed»_space; major characteristics include large mandible, hands, feet, nose and ears
acromegaly
caused by severe hyposecretion of thyroid hormone
cretinism
slight variations in form, position or attachments common and usually insignificant
vestigial and accessory muscles typically asymptomatic
anomalies of skeletal muscles
shortened sternocleidomastoid
thought to be due to birthing trauma but genetics and/or fetal developmental position may also play a role
congenital torticollis (wry neck)
(cleft hand/foot) failure of one or more digital rays to develop»_space; results in hand/foot being divided into two parts that oppose each other
ectrodactyly
shortness of phalanges»_space; autosomal dominant trait
brachydactyly
supernumerary digits»_space; common autosomal dominant trait
polydactyly
two or more digits fused together
can be cutaneous or osseous
syndactyly
foot turned medially and inverted
multifactorial inheritance (genetics plus in utero position)
congenital talipes (clubfoot)
capsule of hip relaxed and underdevelopment of head of femur»_space; dislocation occurs during birth
congenital hip dislocation
complete and partial absence of limb»_space; extremely rare other than due to thalidomide
amelia and meromelia
small brain and cranium but normal sized face
results in gross mental retardation
can be due to autosomal recessive gene or environmental factors such as in utero infection with cytomegalovirus
microcephaly
failure of cleavage of the cerebrum
affected infants usually die within 6 months
several genes have been implicated with environmental influences
holoprosencephaly
most of infant’s brain exudes from skull»_space; may be left with only brainstem and improper vascularization also present
exencephaly
failure of the bones of the cranium close
cranium bifidum
small defect in which only the meninges containing CSF herniate
cranial meningeocele
large defect in which part of the brain and the meninges herniate
meningoencephalocele
very large defect in which the meninges and a part of the brain contain containing a portion of the ventricular system herniate
meningohydroencephalocele
neural tube defects involving vertebral arches»_space; result from defective closure of caudal neuropore
spina bifida
failure of vertebral arches to fuse in median plane
spina bifida occulta
severe forms of spina bifida in which spinal cord and/or meninges protrudes through defect
spina bifida cystica
sac contains meninges and CSF but spinal cord in normal position
spina bifida with meningeocele
sac contains meninges and spinal cord
spina bifida with meningomyelocele
neural ectoderm remains on surface
rachischis
small cysts found in approximately 1/3 of individuals»_space; only symptomatic if infected
urachal cysts
superior or inferior portion of urachus remains patent, opening at either umbilicus or bladder respectively
urachal sinus
rare condition in which entire urachus remains patent»_space; provides mechanism for urine to escape through umbilicus
urachal fistula
failure of testis to descend through abdominal wall
cryptorchidism
testes pass through inguinal canal, but do not migrate into scrotum
ectopic testes
anomalies can results in inguinal hernia and hydrocele
normally closes during perinatal period,
however this doesn’t always happen
fate of the inguinal canal
urethral orifice located along the ventral surface of the penis
hypospadias
female fetus produces excessive amounts of androgens (most commonly due to congenital adrenal hyperplasia) causing masculinization to external genitalia
female pseudohermaphroditism
heart moved to right and inverted like a mirror image the right side of the body»_space; caused by improper initial bending of heart tube
dextrocardia
heart only organ moved to opposite side of body
isolated dextrocardia
heart and abdominal viscera mirror imaged to opposite side of body
dextrocardia situs inversus
heart located external to thoracic cavity
due to failure of lateral folds to properly close + agenesis of the sternum and loss of pericardial cavity
in no other major defects present»_space; attempt to cover with skin
ectopia cordis
due to anomalies of septum primum or septum secundum
ostium secundum ASDs
septum primum fails to fuse with endocardial cushions thereby not closing foramen primum
endocardial cushion defect with patent foramen primum
located near opening of superior vena cava»_space; septum did not fully partition sinus venosus
sinus venosus ASDs
no partitioning of atria due to all of the above ASDs in the infant
common atrium
most common type of significant heart anomaly
ventricular septal defects
failure of truncal ridges to form spiral septum
results in a single trunk that allows mixing of right and left ventricular blood or pulmonary arteries branch off of aorta (slide 20)
can also have unequal division of the truncus arteriosus
persistent truncus ateriosus
most common form of cyanotic heart disease in newborns
aorta empties right ventricle and pulmonary trunk empties left
ventricle
typically accompanied by ASDs and VSDs, and possibly patent ductus ateriosus
transposition of the great vessels
coloboma of the iris»_space; can be a genetic trait
failure of optic fissure to complete close
rare defect in which portions/remnant of hyaloid vessels remain intact
persistent hyaloid artery
opaque dot on lens where hyaloid artery attached
Mittendorf’s dot
opaque lens
congenital cataracts
can be genetic or caused by a teratogen (rubella or radiation most common)
inner and outer layers fail to fuse
congenital retinal detachment
occurs between pigmented epithelium and neural retina
non-congenital retinal detachment
typically presents as a small notch in superior eyelid
coloboma of the eyelids
from malformation of external or middle ear
conducting deafness
from malformation of inner ear
sensineural deafness
most common cause with multiple genes involved
genetic
malformation of organ of Corti
Rubella
general term for a group of hyper-keratinization disorders»_space; dry, fish-like scaling of skin
ichthyosis
genetic recessive trait where skin and hairs lack pigment
albinism
genetic dominant trait resulting in patches of albinism
piebaldism
benign skin tumors resulting from the overgrowth of small blood vessels »_space; typically enlarge for a few months after birth and then shrink and disappear by 5-10 years
infantile angiomas
excessive development of mammary glands in males
gynomastia
supernumerary breasts
polymastia
supernumerary nipples
polythelia
present at birth»_space; painful nursing, lacerate tongue or can fall out and be aspirated
natal teeth
results in pits and/or fissures in teeth
underlying causes = rickets, tetracycline, infectious diseases and idiopathic
enamel hypoplasia
spherical masses of enamel formed by aberrant masses of ameloblasts
enamel pearls
supernumerary teeth that develop in area of maxillary incisors»_space; may disrupt eruption or position of normal teeth
mesiodens
one or more teeth absent»_space; familial trait
partial anodontia
rare condition resulting from congenital ectodermal dysplasia
complete anodontia
fusion of two adjacent teeth (most common) or partial splitting of a single tooth during development
macrodontia
yellowish/brown teeth resulting from hypocalcification of enamel»_space; dominant inheritance
ameliogenesis imperfecta
brown or bluish gray teeth resulting from hypocalcification of dentin
dominant inheritance and fairly common among Caucasians
dentiogenesis imperfecta
foreign materials incorporated into forming enamel
discolored teeth
lue/black teeth due to incorporation of hemoglobin
hemolytic disease of newborns
results in greenish teeth
hyper bilirubinemia
maternal use can result in brown/yellow coloring of teeth
tetracyclines
